One illustrative integrated circuit product disclosed herein includes a single diffusion break (SDB) isolation structure positioned between a first fin portion and a second fin portion, wherein the first fin portion comprises a first end surface and the second fin portion comprises a second end surface. In this example, the SDB structure includes a conformal liner layer that engages the first end surface of the first fin portion and the second end surface of the second fin portion, an insulating material positioned on the conformal liner layer, a cap structure positioned above an upper surface of the insulating material and an air gap positioned between a bottom surface of the cap structure and the upper surface of the insulating material.